A novel monosodium-glutamate-based flame retardant containing phosphorus for cotton fabrics

Abstract A novel bio-based flame retardant ammonium salt of sodium glutamate tetramethylenephosphonic acid (ASGTMPA) was synthesized for cotton. The structure of ASGTMPA was characterized by nuclear magnetic resonance. When the concentration of ASGTMPA was 30%, the limit oxygen index of treated cotton fabric reached 39.5% and was 26.3% after 50 laundering cycles. TG and TG-IR results suggested that ASGTMPA-treated cotton remarkably promoted dehydration of cellulose to form char and reduced production of flammable volatiles. Cone calorimetry and thermogravimetry tests indicated that the ASGTMPA-treated cotton fabric had a lower decomposing temperature and promoted char formation, with peak heat release rate and total heat release lower than those of unfinished cotton fabrics. In a vertical flammability test, the treated cotton fabric showed no after-flame or after-glow, and the char length was 35 mm. The Fourier-transform infrared spectra showed that ASGTMPA combined with cellulose through P–O–C and –COOC– covalent bonds. SEM images revealed that the morphologies of the original and treated cotton fibers were similar. Graphical abstract